Gas turbine, reciprocating engine, steam turbine. Differences depends among other thins on the possible maximum temperatures of the working medium in each process and that depends on the materials used. Another important thing is internal friction in reciprocating engines and gas leakages in turbo compressors gas turbines and steam turbines and those leakages are relatively seen much higher in small machines unless you make them for extremely high speed. However one of the real great problems is as usual tar and ash. Tar will get stuck on the blades of turbo compressors used for gas turbines and some high performance reciprocating engines so that the performance will become worse. Ash could melt and stick to the turbine blades of gas turbines. In addition there are thermal losses in the gasification process and any cleaning of the gas and those losses are not smaller than the losses in wood fired steam process. So the total result is that for small plants it is seems more efficient to use rather robust and simple reciprocating engines without compressors and for bigger and large plants (multi MW)one could just as well burn the wood in boilers. Another ting to remember is that for small gas turbines with moderate compression ratio it might be necessary to use heat exchangers to recover heat between the expanded but still hot exhaust gas and the compressed combustion air. A comparably big wood gasification - 18 MW - plant was built and tested at Varnamo in Sweden during the 1990-ies. It was quite advanced with a combi-process which means a gasturbine folloved by a steam plant with a steam turbine. In order to make it less sensitive to impurities in the gas they used a reciprocating compressor as far as I remember. Today this plant has been rebuilt to become a research center for biomass gasification and the aim is to learn more about gasification and production of biofuels to replace gasoline and dieseloil. You can check their homepage at www.vvbgc.se
Regards Bjorn Dahlroth -----Ursprungligt meddelande----- Från: [email protected] [mailto:[email protected]] För [email protected] Skickat: den 29 november 2010 21:00 Till: [email protected] Ämne: Gasification Digest, Vol 3, Issue 14 Send Gasification mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenerg ylists.org or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of Gasification digest..." Today's Topics: 1. Re: Combustion vs. gasification (Robert Kana) 2. Re: Combustion vs. gasification (Kevin) 3. Re: Combustion vs. gasification ([email protected]) ---------------------------------------------------------------------- Message: 1 Date: Mon, 29 Nov 2010 10:26:57 +0700 From: Robert Kana <[email protected]> To: [email protected] Subject: Re: [Gasification] Combustion vs. gasification Message-ID: <[email protected]> Content-Type: text/plain; charset=UTF-8; format=flowed Good morning, Does anybody know any scientific comparison between combustion and gasification? Argument is that wood chips fired steam boilers and turbines are more efficient than syngas fired duel fuel diesel generators. Any manufacturer has gas turbines small enough to use in 2 MW power generating? Thanks in advance, Robert Kana, Biomass Energy Indonesia ------------------------------ Message: 2 Date: Mon, 29 Nov 2010 01:34:24 -0400 From: "Kevin" <[email protected]> To: "Discussion of biomass pyrolysis and gasification" <[email protected]> Subject: Re: [Gasification] Combustion vs. gasification Message-ID: <d4ada77f37e449379fd0b2daca8eb...@usera594fda0bf> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Dear Robert ----- Original Message ----- From: "Robert Kana" <[email protected]> To: <[email protected]> Sent: Sunday, November 28, 2010 11:26 PM Subject: Re: [Gasification] Combustion vs. gasification > Good morning, > Does anybody know any scientific comparison between combustion and > gasification? Combustion is the purposeful burning of a fuel, while gasification is the conversion of a solid or liquid fuel into a fuel gas, for subsequent combustion. Argument is that wood chips fired steam boilers and > turbines are more efficient than syngas fired duel fuel diesel generators. # "Syngas" is generally intended to mean "a gas mixture used for the synthesis of another product." The term is often used very loosely... "wood gas" is generally not "synthesis gas", because of contained impurities and dilutent nitrogen. The arguement presented above is likely wrong, in that a "syngas" would have a definite composition, and would likely permit better combustion efficiency than would wood chips, that can vary significantly in moisture content. Ask teh presenters of that arguement to clearly define "efficiency", and ask them to support their claim with a technically valid arguement. Best wishes, Kevin Chisholm Any manufacturer has gas turbines small enough to use in 2 > MW power generating? Thanks in advance, > Robert Kana, Biomass Energy Indonesia > > _______________________________________________ > Gasification mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenerg ylists.org > > for more Gasifiers, News and Information see our web site: > http://gasifiers.bioenergylists.org/ > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1170 / Virus Database: 426/3285 - Release Date: 11/28/10 > ------------------------------ Message: 3 Date: Mon, 29 Nov 2010 05:57:46 +0000 From: [email protected] To: "Discussion of biomass pyrolysis and gasification" <[email protected]> Subject: Re: [Gasification] Combustion vs. gasification Message-ID: <w9789176178661291010...@webmail8> Content-Type: text/plain; charset="us-ascii" Robert, >From our work on this subject, the gasification/Otto cycle is the most efficient for small and medium sized facilities, The efficiencies converge as the plants get bigger. We have looked at the Diesel cycle via dual fueled engines but there is no experience on this combination for producer gases. For gases from pyrolysis, the experience is still very limited. It can be done if you use enough Diesel fuel, but it might not be cost effective. The most experience is with Otto cycle configurations, but even that is limited. Advantage of the steam cycle is that is proven. But efficiency is lower. For 2MW gas turbine, I would recommend an older version of the Solar Centuar 40. They would be about 2 MW at site conditions. Try the Woods Group as a source for these machines. Best Regards, Jim Leach, P.E. -----Original Message----- From: Robert Kana [mailto:[email protected]] Sent: Sunday, November 28, 2010 07:26 PM To: [email protected] Subject: Re: [Gasification] Combustion vs. gasification Good morning, Does anybody know any scientific comparison between combustion and gasification? Argument is that wood chips fired steam boilers and turbines are more efficient than syngas fired duel fuel diesel generators. Any manufacturer has gas turbines small enough to use in 2 MW power generating? Thanks in advance, Robert Kana, Biomass Energy Indonesia _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenerg ylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ -------------- next part -------------- An HTML attachment was scrubbed... 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